1. Field of the Invention
The present invention relates to a method utilized in a wireless communication and communication device thereof, and more particularly, to a method of reconfiguring parameters of a medium access control (MAC) layer in a wireless communication system and communication device thereof.
2. Description of the Prior Art
A long-term evolution (LTE) system, initiated by the third generation partnership project (3GPP), is now being regarded as a new radio interface and radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs) and communicates with a plurality of mobile stations, also referred as user equipments (UEs).
A radio interface protocol of the LTE system includes three layers: the Physical Layer (L1), the Data Link Layer (L2), and the Network Layer (L3), wherein a control plane of L3 is a Radio Resource Control (RRC) layer, and L2 is further divided into a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer and a Medium Access Control (MAC) layer.
Main services and functions of the MAC layer include mapping between logical channels and transport channels; multiplexing/demultiplexing of PDUs (Packet Data Units) belonging to one or different radio bearers into/from transport blocks (TBs) delivered to/from the physical layer on transport channels; buffer status reporting; power headroom reporting; error correction through HARQ; priority handling between logical channels of one UE; discontinuous reception (DRX); priority handling between UEs by means of dynamic scheduling; and padding.
Various MAC parameters, such as timers and counters, are employed for the abovementioned functions/services and are configured or reconfigured by the RRC layer. In RRC (re)configuration, the MAC parameters are grouped into a “MAC-MainConfiguration” information element (IE). When the MAC parameters of the UE are reconfigured by the RRC layer of the EUTRAN, two ways are used for reconfiguration of MAC parameters. In the first way, the UE receives the MAC parameters from broadcasted system information and then receives MAC parameters from dedicated RRC signaling, e.g. a RRC CONNECTION RECONFIGURATION message. In the second way, the UE only receives the MAC parameters from dedicated RRC signaling, e.g. a RRC CONNECTION RECONFIGURATION message.
In DRX parameters of the “MAC-MainConfiguration” IE, a short DRX parameter has choices of ‘disable’, ‘NULL’, and ‘enable’. When the short DRX parameter is set to ‘disable’, a short DRX cycle is possibly still configured with a value, and thereby the short DRX parameter is not substantially disabled, but only nominally. This causes a system error.
The MAC parameters may be reconfigured when they are in use. According to the prior art, the reconfigured MAC parameters is required to be applied immediately. For example, a timer value is received for reconfiguration of a currently-running timer. The timer is immediately restarted with the reconfigured timer value. However, enforcing a newly-reconfigured value on an in-use MAC parameter can cause errors of corresponding function/system or impact communication system performance.